"It's been a great run but all good things must come to a end," Harrison wrote. "Thank you Steelers Nation I will miss you all!"

The team confirmed the move later Saturday morning.

"James has been an integral part of our success during his years in Pittsburgh and has helped us win two Lombardi trophies during that time. We appreciate all of his efforts and wish him the best," GM Kevin Colbert said in a statement.

Added coach Mike Tomlin: "James has played a major role in the success of this organization during his time in Pittsburgh. I appreciate everything he has done in my six years as head coach and wish him nothing but the best in the future."

Harrison was owed a base salary of $6.57 million this upcoming season, one year after he recorded six sacks in 13 games. Harrison battled a knee issue last season and turns 35 in May.

The Steelers were $1.4 million over the adjusted salary cap at the end of this work week. Harrison's release will put them under the cap, as it provides about $5 million in cap relief.

Harrison's agent Bill Parise told USA TODAY Sports on Saturday afternoon he's already "had some conversations" with other teams, though he declined to name the clubs. Parise is hopeful Harrison will find a new job quickly.